CN203850835U - A suppression system for induced current and voltage between double-circuit lines on the same tower - Google Patents

Abstract

A suppression system for induced current and voltage between double-circuit lines on the same tower, which includes two substations connected to line I and line II respectively and their grounding switch control system, between the grounding switch of the first substation and the ground network One impedance is set in series, and one contactor is connected in parallel with the impedance. The utility model achieves the purpose of suppressing the induced current without increasing the line voltage by adopting a parallel system of impedance-contactors connected in series between the grounding switch and the ground network of the substation. In order to reduce the complexity of the operation during maintenance, the original The operation circuit of the grounding knife switch is optimized to realize the automatic control of the switching of the contactor connected in parallel with the impedance. The utility model can effectively reduce the electromagnetic induction current, meet the needs of opening and closing large-capacity, long-distance, compact double-circuit power transmission lines on the same tower, and reduce the equipment cost; and also provide an electromagnetic induction current voltage in the completed substation. The solution that does not need to replace the grounding knife switch when the standard is exceeded.

Description

A suppression system for induced current and voltage between double-circuit lines on the same tower

technical field

The utility model relates to the technical field of transmission line maintenance, in particular to a suppression system for induced current and voltage between double-circuit lines on the same tower.

Background technique

With the development of the power grid and the increasing tension of transmission line corridors, in order to reduce the area occupied by transmission corridors, double-circuit or even multi-circuit transmission lines on the same tower have been widely used. There is strong electrostatic coupling and electromagnetic coupling between the two circuits of the double-circuit transmission line on the same tower. When one circuit is in normal operation and the other circuit is powered off for maintenance, induced current and voltage will be generated on the outage line.

The coupling between the two lines of the double-circuit transmission line on the same tower mainly includes electrostatic coupling and electromagnetic coupling. Assuming that line I is in normal operation and line II is powered off for maintenance, and taking phase A of the maintenance line as the research object, the coupling between lines is shown in Figure 1 As shown in Fig. 2, in Fig. 1 and Fig. 2, C _ⅠAIIA , C _IBⅡA , and C _ICⅡA represent the capacitance per unit length between the three-phase line ⅠABC and the line ⅡA phase, and C _ⅡA represents the capacitance per unit length of line Ⅱ; M _ⅠAIIA , M _{Ⅰ B Ⅱ A} , M _{IC Ⅱ A} represent the mutual inductance per unit length between the three-phase line ⅠABC and the line ⅡA phase, and L _ⅡA represents the self-inductance per unit length of line Ⅱ. Line Ⅰ voltage is U _ⅠA , U _ⅠB , U _IC current is I _ⅠA , I _IB , I _IC ; line ⅡA phase electrostatic induction voltage is U _ⅡSA , electrostatic induction current is I _ⅡSA ; line ⅡA phase electromagnetic induction voltage is U _ⅡMA , electromagnetic induction The current is I _ⅡMA .

As shown in Figure 1, when the grounding switches on both sides of the maintenance line are in the off state, the electrostatic induction voltage plays an important role on the maintenance line, and it is easy to obtain:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; SIA</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; IAIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; IA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; IBIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; IB</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ICIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; IC</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; IAIIA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; IBIIA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ICIIA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

It can be seen from formula (1) that the electrostatic induction voltage is only related to the voltage level and the unbalance of capacitance between phases of the line, and has nothing to do with the length of the line and the transmission power.

When the grounding switch on one side of the maintenance line is in the off state and the grounding switch on the other side is in the closing state, the current flowing on the line is mainly electrostatic induction current, which can be obtained as follows:

I _SIIA ＝jωl(C _IAIIA ·U _IA +C _IBIIA ·U _IB +C _ICIIA ·U _IC ) (2)

It can be seen from formula (2) that the electrostatic induction current is related to the voltage level, the unbalance of capacitance between phases of the line, and the length of the line, but has nothing to do with the transmission power of the line.

As shown in Figure 2, when the grounding switch on one side of the maintenance line is in the disconnected state and the grounding switch on the other side is in the closing state, the voltage on the disconnected side of the line grounding switch is mainly electromagnetic induction voltage, which can be obtained as follows:

U _MIIA ＝jωl(M _IAIIA ·I _IA +M _IBIIA ·I _IB +M _ICIIA ·I _IC ) (3)

It can be seen from formula (3) that the electromagnetic induction voltage is related to the transmission power of the line, the unbalance of the coupling inductance between the phases of the line, and the length of the line, and has nothing to do with the voltage level.

When the grounding switches on both sides of the maintenance line are in the closed state, the current flowing through the line is mainly electromagnetic induction current, which can be obtained as follows:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; MIIA</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IAIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IBIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IB</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ICIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IC</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

It can be seen from (4) that the electromagnetic induction current is only related to the unbalance of the line transmission power and the coupling inductance between the lines, and has nothing to do with the voltage level and the line length.

In order to ensure the safety of the maintenance personnel, when performing maintenance on the double-circuit line on the same tower, the grounding knife switch on both sides of the maintenance line must be closed and the grounding wire must be connected; Ground the knife switch on both sides of the line, and then perform switching operation to transmit power. During the whole process, the grounding switch on both sides of the line needs to be put in first and then withdrawn. During this period, the current and voltage induced from the running line to the maintenance line need to be switched on and off.

Due to the characteristics of the structure of the grounding switch itself, its ability to cut off the current and voltage is very weak. The coupling effect between the double-circuit lines on the same tower has caused a great test to the cutting ability of the grounding switch. performance requirements are more stringent.

At present, according to the requirements of national standards and related enterprise standards, in order to meet the requirements of cutting off different induced currents and voltages, the grounding switch is divided into Class A, Class B, and Super B Class, of which Class A and B are conventional products, and Class Super B is a special product. Customized products, negotiated by the manufacturer and the user, are specially used to cut off the large induced current and voltage, requiring special design, high cost, and complicated operation and maintenance.

In addition, it is also found in practice that the original dual-circuit line on the same tower with conventional grounding switch on both sides, as the load increases, the line is reconnected, and the operating mode is changed, the induced current and voltage of the double-circuit line on the same tower will exceed the standard, resulting in two The grounding switch on the side cannot meet the requirements of cutting off the induced current and voltage of the newly connected line. At this time, it is necessary to replace the grounding switch in the completed substation as a whole. The replacement of equipment in completed substations is restricted by various factors such as site area, equipment form, and power outage construction plan.

Utility model content

In order to solve the above problems, the utility model provides a suppression system for induced current and voltage between double-circuit lines on the same tower, which has a simple structure and can effectively suppress the induced current and voltage between double-circuit lines on the same tower during maintenance.

The technical solution adopted by the utility model to solve the technical problem is: a suppression system for induced current and voltage between double-circuit lines on the same tower, including substations and their grounding knife gate control systems respectively connected to line I and line II, and its characteristics Yes: It also includes impedance and contactors, the substation includes a first substation and a second substation, the grounding switch of the first substation and the second substation is connected to the ground network, and the grounding switch of the first substation An impedance is set in series with the ground grid, and the impedances are respectively connected in parallel with a contactor.

Further, the grounding knife switch control system includes a first time relay and a second time relay, the contacts of the first time relay and the second time relay are respectively set in the contactor control of the primary circuit of the grounding knife switch control system In the loop, the coil is placed in the secondary loop.

Further, the coil of the contactor is connected in series with the contacts of the first time relay and the second time relay, and the contacts are connected in parallel with the contacts of the first time relay.

Further, the contactor adopts a model JCZ5-7.2/400 contactor.

The beneficial effects of the utility model are: the utility model realizes the purpose of suppressing the induced current without increasing the line voltage by adopting the parallel system of the impedance-contactor connected in series between the grounding switch of the substation and the ground network, and reducing the maintenance time. Due to the complexity of the operation, the operation circuit of the original grounding switch is optimized to realize the automatic control of the switching of the contactor connected in parallel with the impedance. Adding the suppression system to the conventional grounding switch can effectively reduce the electromagnetic induction current, meet the needs of opening and closing large-capacity, long-distance, compact double-circuit transmission lines on the same tower, and reduce the cost of equipment; the electromagnetic induction current and voltage of the completed substation exceed the standard At the same time, it also provides a solution that does not need to replace the grounding switch.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Figure 1 is a schematic diagram of electrostatic coupling between double-circuit lines on the same tower;

Figure 2 is a schematic diagram of electromagnetic coupling between double-circuit lines on the same tower;

Fig. 3 is a schematic diagram of the device connection structure of the suppression system of the present invention;

Fig. 4 is the primary loop circuit diagram of suppression system described in the utility model;

Fig. 5 is the secondary loop circuit diagram of suppression system described in the utility model;

Fig. 6 is a schematic structural diagram of a grounding knife switch connected in series only with impedance;

Fig. 7 is a simulation curve diagram of the electromagnetic induction current of the 500kV line changing with the resistance when the grounding switch is only connected in series with impedance;

Fig. 8 is a simulation curve diagram of the voltage at the resistance terminal of a 500kV line changing with resistance when the grounding switch is only connected in series with impedance.

Detailed ways

The following disclosure provides many different embodiments or examples for realizing different structures of the present invention. To simplify the disclosure of the present invention, components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in different instances. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. It should be noted that components illustrated in the figures are not necessarily drawn to scale. The present invention omits descriptions of known components and processing techniques and processes to avoid unnecessarily limiting the present invention.

As shown in Figure 3, Figure 4 and Figure 5, a system for suppressing induced current and voltage between double-circuit lines on the same tower of the present invention includes a substation and a grounding switch control system respectively connected to Line I and Line II, and Including an impedance and a contactor, the substation includes a first substation and a second substation, the grounding switches of the first substation and the second substation are connected to the ground grid, and the grounding switch of the first substation is connected to the ground grid An impedance is set in series between them, and the impedances are respectively connected in parallel with a contactor; the grounding knife switch control system includes a first time relay and a second time relay, and the contacts of the first time relay and the second time relay are respectively It is arranged in the contactor control circuit of the primary circuit of the grounding knife switch control system, and the coil is arranged in the secondary circuit; the coil of the contactor is connected in series with the contacts of the first time relay and the second time relay, and the contacts and The contacts of the first time relay are connected in parallel. The contactor adopts a model of JCZ5-7.2/400 contactor.

During maintenance of double-circuit lines on the same tower, the suppression system described in the utility model is used to suppress the induced current and voltage between the double-circuit lines on the same tower. The operation process is as follows:

1) An impedance is connected in series between the grounding switch and the ground network of the first substation, and each impedance is connected in parallel with a contactor, and the contactor is out of the opening state;

2) Before maintenance, first close the grounding switch of the second substation, and then close the grounding switch of the first substation. At this time, the grounding switch of the first substation is connected to the ground network through the serial impedance;

3) Close the contactor, short the impedance, and carry out line maintenance;

4) After the maintenance is completed, first disconnect the contactor, connect the impedance in series between the grounding switch of the first substation and the ground grid, and then disconnect the grounding switch of the first substation and the grounding switch of the second substation in turn.

The working principle of the present utility model is as follows.

Both theoretical calculation and actual measurement prove that the coupling capacitance and coupling inductance between the double-circuit lines on the same tower are very small, the capacitance value is on the order of microfarads, and the coupling inductance is on the order of millihenries. Analyzing formula (2) and formula (3), it can be seen that due to the small coupling capacitance and coupling inductance, the electrostatic induced current and electromagnetic induced voltage are very small, which are secondary factors in the research of induced current and voltage. Analyzing formula (1) and formula (4), it can be seen that although the coupling capacitance and coupling inductance are relatively low compared with the line's own capacitance and inductance, they still have a certain ratio when divided, so the electrostatic induction voltage and electromagnetic induction current relatively bigger. Further analysis, because the voltage of the system is often controlled at a stable value, so for a line of a certain voltage level, the electrostatic induction voltage is not changed much by the operation mode, generally speaking, it is predictable, and the wire is replaced according to the measured results. After taking some measures, the electrostatic induction voltage can be limited to an appropriate value. However, it can be seen from formula (4) that the size of the electromagnetic induction current has a great influence on the current of the operating line, and the relationship is linear; and the change of the operation mode, the change of the power flow, and the change of the connection mode in the power system will all have a negative impact on the current of the operating line. The effect is to change the electromagnetic induction current. Generally speaking, it is necessary to calculate the electromagnetic induction current of the out-of-service line according to the limit transmission current of the conductor in operation. According to this standard, the grounding switch can be selected to ensure that the grounding switch can work reliably without damage when opening and closing.

When checking the electromagnetic induction current of the outage line according to the limit transmission current in operation, the three parameters of electrostatic induction voltage, electrostatic induction current and electromagnetic induction voltage are generally not high, which are within the range required by conventional A and B grounding knife switches; The value of the electromagnetic induction current is large, exceeding the requirements of conventional A and B grounding knife switches.

Considering that the coupling inductance is very low, the utility model effectively increases the impedance value of the electromagnetic induction current loop by connecting the impedance in series between the grounding knife switch and the ground grid, thereby achieving the purpose of suppressing the electromagnetic induction current.

As shown in Figure 6, it is assumed that the electromagnetic induction current on the line after connecting the impedance in series is _I'MIIA , and the voltage at the end due to the electrostatic induction current rises to _U'SIIA .

When the grounding switch QE1 is connected in series with impedance Z, the electromagnetic induction current flowing through the line is suppressed:

$\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IAAIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IBIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IB</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ICIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IC</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; j\&omega;l</span>}}}\\ <span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IAIIA</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IBIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IB</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ICIIA</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; IC</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; ad</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

It can be seen from (5) that when the transmission capacity and line parameters do not change, the series connection impedance is equivalent to increasing the self-inductance of the line, thereby reducing the electromagnetic induction current.

However, since the induced current flows through the additional impedance, a voltage will be generated on the additional impedance, thereby raising the potential of the outage line, resulting in the potential increase of the outage line as follows:

${{\mathrm{<span\; class="notranslate">\; u</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; MIIA</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; IIA</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

According to the data of a typical 500kV double-circuit line on the same tower, different resistors are connected in series in the grounding knife switch circuit, and the curves of the induced current voltage (the maximum value in each phase) changing with the resistance are obtained as shown in Figure 7 and Figure 8:

It can be seen from Figure 7 and Figure 8 that after connecting the resistors in series, the electromagnetic induction current decreases sharply with the increase of the series resistance, and at the same time, it will cause a higher potential rise at the end of the series resistance, thereby raising the potential of the power failure line , may cause injury to maintenance personnel. Further analysis shows that the potential at the end of the series resistor increases with the resistance, but it is not higher than the electromagnetic induction voltage when the line is not connected in series. In order to solve the influence of this voltage, as shown in Figure 3, the suppression system of the present invention is composed of an impedance Z and a contactor KM connected in parallel with the impedance Z.

When line II is powered off for maintenance, first close the grounding switch QE2 of the second substation B, then close the grounding switch QE1 of the first substation A, and connect the impedance Z to the system to suppress the closing of the grounding switch QE1 The role of the electromagnetic induction current; after the grounding knife switch QE1 is closed, close the contactor KM, short the impedance Z, and suppress the potential rise on the maintenance line at the same time.

When the line Ⅱ is out of maintenance, first disconnect the contactor KM, connect the impedance Z to the system, and suppress the large electromagnetic induction current when the grounding knife switch QE1 is opened; then disconnect the grounding knife switch QE1 and the grounding knife switch QE2 in sequence Ground the knife switch and exit the maintenance line.

For a typical 220-500kV split conductor, the line self-inductance L≈1.7×10 ^-3 H/km, which is relatively small. It can be seen from formula (5) that the magnitude of the electromagnetic induction current is basically inversely proportional to the resistance value of the series resistor. set up When k=2, that is, Z _ad2 =L, the electrostatic induction current will be reduced to 50% of the original. According to the self-inductance value of the line increased above, the corresponding series resistance Z=0.5338l. For a 40km 220kV line, the series resistance is about 22Ω; for a 100km 500kV line, the series resistance is about 53Ω.

According to the simulation curves shown in Figures 7 and 8, it can be seen that when the series resistances are 20Ω and 50Ω, the corresponding electromagnetic induction current is basically reduced by half, and the simulation results are consistent with the theoretical analysis.

When the maintenance line grounding switch is closed, then the parallel contactor will short-circuit the series resistance. At this time, the current flowing through the contactor is all electromagnetic induction current. Before the grounding switch of the maintenance line is disconnected, the parallel contactor needs to be disconnected first, so the parallel contactor must have the ability to break all electromagnetic induction currents. When the contactor is disconnected, it needs to withstand the voltage on the series resistor, which will not exceed the electromagnetic induction voltage of the line according to the above analysis.

Considering that the electromagnetic induction current of general lines does not exceed 300A, and the electromagnetic induction voltage of 220-500kV lines is generally not greater than 6.3kV, the JCZ5-7.2/400 type contactor can be selected. The rated operating voltage of this type of contactor is 7.2kV, the rated operating current is 400A, the closing current can reach 4kA, and the breaking current can reach 3.2kA.

As shown in Figure 4 and Figure 5, in order to reduce the complexity of the operation, the control circuit of the grounding knife switch is optimized. In Figure 4 and Figure 5, T1 and T2 are time relays, and KM1 and KM2 are grounding knife switch QE Control loop, KM3 is the control loop of contactor KM. By adding a time relay to the original grounding knife switch control circuit, the contactor can be automatically put into operation after the grounding knife switch is closed, and the contactor is automatically disconnected before the grounding knife switch is disconnected, which simplifies the operation process.

The above is only a preferred embodiment of the utility model, and for those of ordinary skill in the art, without departing from the principle of the utility model, some improvements and modifications can also be made, and these improvements and modifications are also regarded as It is the protection scope of the utility model.

Claims (4)

1. A suppression system for induced current and voltage between double-circuit lines on the same tower, including substations connected to line I and line II respectively and their grounding switch control systems, characterized in that: also include impedance and contactors, said substation Including a first substation and a second substation, the grounding switch of the first substation and the second substation are connected to the ground grid, and an impedance is set in series between the grounding switch of the first substation and the ground grid, the The impedances are respectively connected in parallel with a contactor. 2. A system for suppressing induced current and voltage between double-circuit lines on the same tower according to claim 1, characterized in that: said grounding switch control system includes a first time relay and a second time relay, and said first The contacts of the time relay and the second time relay are respectively arranged in the contactor control circuit of the primary circuit of the grounding knife switch control system, and the coil is arranged in the secondary circuit. 3. A suppression system for induced current and voltage between double-circuit lines on the same tower according to claim 2, characterized in that: the coil of the contactor is connected in series with the contacts of the first time relay and the second time relay, The contacts are connected in parallel with the contacts of the first timing relay. 4. A system for suppressing induced current and voltage between double-circuit lines on the same tower according to any one of claims 1 to 3, characterized in that: said contactor adopts a contactor of model JCZ5-7.2/400.